Slide Author - M.L.Dunzik-Gougar

Why are we concerned about Radiation?

Ionizing Radiation

Human Cells

Atoms in Cells Form Ions

Change in Cell Cell DiesNo Change in Cell

Not Replaced

ReplacedReproduces

Malignant Growth Benign Growth

Biological Effects of Radiation

• Biological Effects of Radiation can be broken into two groups according to how the responses (symptoms or effects) relate to dose (or amount of radiation received)

• The First Group of biological effects are Stochastic Effects

• The Second Group of biological effects are Deterministic Effects

Deterministic Effects

• Deterministic Effects are those responses which increase in severity with increased dose

• For example; sunburn. The more you’re exposed to the sun, and the higher the ‘dose’ of sunlight you receive, the more severe the sunburn

Stochastic Effects

• Stochastic Effects are those effects which have an increased probability of occurrence with increased dose, but whose severity is unchanged

• Example; skin cancer and sunlight. The probability of getting skin cancer increases with increasing exposure to the sun

• Stochastic Effects are like a light switch; they are either present or not present

Background Radiation

• As a part of living on earth, people are exposed to radiation from various sources every day

• Some of this radiation comes from:– Radon Gas– Space (in the form of cosmic rays)– The earth (from the rocks and soil)– Ourselves (from radioactive carbon and potassium in

our bodies)– Medical Procedures (X-rays, etc)

Comparison of Radiation Dose

1 10 100 1000 10000 100000 1000000

Lethal Dose

Radiation Worker Limit

Natural Background

Average PSU RSEC Worker

Chest X- Ray

Average Annual Dose- United States

RadonCosmicTerrestrialInternalMedical X-raysNuclear MedicineConsumer ProductsOther

Annual Dose

RadonCosmicTerrestrialInternalMedical X-raysNuclear MedicineConsumer ProductsOtherFrom Nuclear Facility

NRC Limits

Subjects Exposed Time Frame Dose (mrem)

Nuclear Worker 1 year 5000

General Public (from Nuclear Facility) 1 year 100

Pregnant Woman 9 months 500